The law is intended to eliminate what the lawmakers consider is a market preference for Wall Street megabanks. The market, they charge, knows that the American tax payer is on the hook for Wall Street excess. To change that, the law forces banks to hold a certain amount of capital depending on their balance sheet. Community/regional banks have to hold cash equivalent to 8% of assets on their balance sheets. For big banks the magic number's 15%.

So we know the "why" of this bill... but the more important question is "why now?" The financial crisis is abating, regulations like Dodd-Frank, The Volcker Rulle, and Basels I-III already require banks to stop some of the activities that led to the crisis.

The thing is, there have been signs that this was coming — signs that anger at Wall Street was growing on both sides of the aisle.

House Financial Services Committee, FacebookThat's what is key here: The fragmentation of the Republican party into your traditionals (think: John McCain) and your Libertarians (think: Rand Paul) has made room for different thoughts about the relationship between Wall Street and the GOP.

"I'm going to steer this party away from Wall Street and toward what used to be called Main Street and doesn't have a name anymore. Our economy won't take off again until our pigsty of a tax code is cleaned up. People have to feel everyone's being treated fairly, that the rich aren't calling the shots and gaming the system. And all future growth could be stymied if you guys make a half-trillion-dollar wrong bet tomorrow because some trader in London was high as a kite on Ambien. That could bring down the system the way it crashed in '08. So we have to change the system. Too big to fail is too big to live."

If that wasn't enough, then Attorney General Eric Holder admitted that 'Too Big To Fail' was real — something Wall Street's advocates had fiercely denied. He said the Justice Department had held off on prosecuting banks for their misdeeds because the agency feared what would happen to the financial system as a whole.

"That is a function of the fact that some of these institutions have become too large," said Holder. Adding that the size of Wall Street's biggest banks "has an inhibiting influence - impact on our ability to bring resolutions that I think would be more appropriate...And I think that is something that we - you all - need to consider."

If that's not too big to fail, nothing is.

There's more though — like Rand Paul's raucous speech at the CPAC Convention when he said that there was "nothing conservative about bailing out Wall Street."

That's a message that resonates with Tea Partiers and Libertarians. And it's a message that Brown and Vitter are zeroing in on for this bill. In a video released this morning, Brown explains:

"If megabanks want to be large and complex that's their choice but tax payers should not have to subsidize their risk taking. If big banks fail their executives and investors should have to pay the price."

Even Jamie Dimon said that "Old Testament Justice" should rain down on those who fly their banks into a mountain.